Herbicidal 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid and salts thereof, and various herbicidal derivatives of these compounds have been proposed including alkyl and cycloalkyl esters, alkylthio esters, phenyl ester, alkyl and dialkyl amido and benzoyl chlori forms. U.S. Patents which describe such compounds and the like include U.S. Pat. Nos. 3,652,645; 3,784,635; 3,873,302; 3,983,168; 3,907,866; 3,798,276; 3,928,416; and 4,063,929. The published European Patent Application 3,416 to ICI describes various alkylsulfonamide derivatives of 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid including, inter alia, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitro-N-methanesulfonyl benzamide. The published European Patent Application 20,052 to Rohm and Haas and the published UK Patent Application 2,058,055A to PPG describe various alkoxycarbonylalkyl esters of 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid.
According to a particular herbicidal treatment it has been proposed to apply sodium 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate to soybean fields in post-emergence applications to control certain weeds such as broadleaf weeds, e.g., velvetleaf, cocklebur and morningglory. Accordingly, there is a need in the art to provide methods for controlling grass weeds such as johnsongrass.